Breakerless ignition control unit



June 27, 1967 J, F L ETAL 3,32,61

BREAKERLESS IGNITION CONTROL UNIT Filed Aug. 24, 1964 2 Sheets Sheet 1 INVENTORf? Jail/r Hi fw/ge BY @emm' (2i Hemfzmger G J WU) June 27, 1967 .1. H. FALGE ET AL- 3,328,614

BREAKERLESS IGNITION CONTROL UNIT Filed Aug. 24, 1964 2 Sheets-Sheet 2 I N VEN TORS John H. F a/ge BY Gerald Of/umz/hger The/r Aflorney United States Patent 3,328,614 BREAKERLESS IGNITION CONTROL UNIT John H. Falge and Gerald D. Huutzinger, Anderson, Ind., assignors to General Motors Corporation, Detroit, Micln, a corporation of Delaware Filed Aug. 24, 1964, Ser. No. 391,583

2 Claims. (Cl. 31070) ,This invention relates to a breakerless ignition control unit for controlling the operation of a semiconductor ignition system for an internal combustion engine.

The present invention is concerned with a breakerless distributor wherein the conventional breaker contacts of the distributor are replaced by an assembly which includes a pick-up coil and a permanent magnet. The conventional breaker cam is used to control the flow of flux in a magnetic circuit which causes voltage pulses to be induced in the pick-up coil that can be used to control a semiconductor ignition system of the type illustrated in the Short et al. patent, 3,087,001.

One of the objects of this invention is to provide an ignition control unit of the type described where means are provided for reducing the likelihood of producing a false triggering signal from the breakerless distributor due to stray field pick-up, voltage transients and other disturbances. In carrying this object forward, the length of the conductors between the pick-up coil and a first amplifying stage are made as short as possible so as to reduce the likelihood of false triggering from the conditions mentioned above. This is accomplished by mounting the first amplifier stage in the distributor adjacent the pickup coil.

Another object of this invention is to provide an asreluctance of the magnetic circuit.

Further objects and advantages of the presentinvention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown. I

In the drawings:

FIGURE 1 is a view partly in section of a breakerless distributor made in accordance; with this invention and taken along line 1'1 of FIGURE 2.

FIGURE 2 'is a sectional view of a distributor made in a-ccordancewith this invention.

FIGURE 3 is a schematic circuit diagram of an ignition system which uses the breakerless distributor and amplifier of this invention.

Referring now to'the drawings and more particularly engine. The shaft 12 drives a conventional centrifugal advance mechanism 14 which drives a conventional breaker cam 16. The breaker cam 16 as is well known to those skilled in the art is adjusted relative to the shaft 1 2 by the centrifugal advance mechanism 14 in accordance with shaft speed.

The base 10 of the distributor carries a plate 18 and this plate pivotally supports a breaker plate 20. This pivotal connection is provided by a pin 22 carried by the fixed plate 18, the breaker plate 20. i

The base 10 carries a conventional distributor cap 24 having the usual center electrode 26 and a plurality of circumferentially spaced electrodes 28 that are connected with the spark plugs of the engine by suitableconductors (not illustrated).

The breaker cam 16 carries a rotor 30 which carries two conductors forming a rotor contact 34 which connects the center electrode 26 of the distributor cap with the inserts or electrodes 28 as the rotor rotates.

The timing plate 20 can be adjusted relative to the fixed plate 18 by a vacuum unit 36 having the usual diaphragm connected with an actuating link 38. The link 38 is connected with the timing plate 20 and the vacuum unit is connected with the intake manifold of the engine as is well known to those skilled in the art.

The distributor as thus far disclosed is conventional and this invention is concerned with providing a device which generally designated by reference numeral 40 is provided which includes a magnetic pick-up coil, a permanent magnet and a transistor amplifier.

The assembly 40 includes an nated'. by reference numerals and 3.

It is seen from an inspection of FIGURE 3 that the mitter of transistor 62 is grounded. The collector of is connected to junction 68 and diode 70,

69 between resistor the opposite side of diode 70 being grounded. The other.

the pin passing through an opening in which might cause a The conductors 74 and 76 are used to control a system which includes PNP transistors 82, 84 and 86. The transistors 82, 84 and 86 are connected across a conductor 88 and ground, the conductor 88 being connected with the output conductor 74 of the amplifier 80. A direct current voltage is applied between conductor 88 and ground by a source of direct current 90 when a manually operable switch 92 is closed.

The emitters of transistor 82 and 86 are connected with conductor 88 while the, emitter of transistor 84 is connected with conductor 88 through a resistor 94. A junction 96 connected with the emitter of transistor 84 is connected with the base of transistor 86 by a conductor 98. The base of transistor 84 is connected with the collector of transistor 82 by a capacitor 100. The base of transistor 82 is connected with the collector of transistor 84 by a resistor 102. The collector of transistor 82 is connected to ground through a resistor 104 and the resistor 106 connects the collector of transistor 84 to ground. A resistor 108 connects the base of transistor 84 to ground.

The collector of transistor 86 is connected to one side of the primary winding 110 of an ignition coil 112. The secondary winding 114 of the ignition coil has one side connected with high voltage conductor 116 and has its opposite side connected with a grounded junction 118. The conductor 116 is connected with the rotor contact 34 which sweeps past the inserts 28 of the distributor cap 24. The inserts 28 feed a plurality of spark plugs for the engine, one of which is designated by reference numeral 120.

A Zener diode 122 is connected across the emitter and collector electrodes of the transistor 86.

When the switch 92 is closed, the ignition system will be energized and if the engine is being cranked or running, the cam 16 and the rotor 30 are driven by the engine through the shaft 12 as is well, known to those skilled in the art.

With the switch 92 closed, currentcan flow from the positive side of battery 90, through conductor 88, through conductor 74, through resistor 68 and through diode 70 to ground. The junction 69 will be positive with respect to ground and the base, of transistor 62 will therefore be somewhat positive with respect to its emitter. The components of the system are selected such that the bias applied to transistor 62 from thejunction.

69 when no voltage is induced in pick-up coil 56 biases the transistor 62 to a point where the transistor isalmost turned on. When a pulse ofvoltage is now induced in the pick-up coil 56 whichdrives the base. of the transistor 62 more positive, the transistor 62 is turned on in its collector-emitter circuit and current can then flow from conductor 74, through resistor 66, through resistor 64,. and through the collector-emitter circuit of thetransistor 62 to ground.

The voltage drop one of the spark plugs 120 via conductor 116, electrode- 26, through contact 34. and one of the inserts 28 of the distributor cap 24.,It is noted that transistor 86 wasconductive for a period of time before it is. turned off and when it is conductive, current flows from conductor 88, through the emitter-collector circuit of transistor 86, and.

through the primary winding 110, to ground. The. switching action of transistors 82, 84 and 86 together with thecomponents connecting these transistors is described in the United States Patent to Short et al., 3,087,001.

When the voltage reversesin thefpick-up coil.56, the.

transistor 62 will be biased to a rit ncor1ductivev condition which will turn off the transistor 82. Whenftransistor 82 developed across resistor 66 when. transistor 62 is conductive, will bias the transistor 82 to turns off, the capacitor can recharge through resistor 104. When capacitor 100 discharges through resistor 108, the turn-off bias for transistor 84 ceases and transistors 84 and 86 can turn back on so that current can then flow through transistor 86 and through the primary winding of the ignition coil 112.

When the cam 16 rotates, it varies the reluctance of a magnetic circuit which. is from one end of the permanent magnet 46, through the upstanding portion 44, through the horizontal section 42 of the bracket, through timing plate 20, through the air gap between plate 20 and the lower edge of the cam 16, through the cam 16, through the pole tip 54, through core'52, and through the part 48 to the opposite side of the permanent magnet 46. When a lobe 16a of the cam is aligned with the pole tip 54, the maximum amount ofmagnetic flux will traverse the magnetic circuit and thisflow of magnetic flux will be reduced as a lobe 16a swings away from the pole tip 54.

The pulse of voltage which turns on the transistor 62 is induced in the pick-up coil 56 when one of the cam lobes 16a leaves the end'of the projection 54. The voltage that is induced in pick-up position substantially midway a pair of lobes 16a or in other words, when the cam 16 rotates to a position approximately one-half the distance to the next cam lobe.

The transistors 62 and 82 will turn on and transistors 84 and 86 will turn off when'cam lobe 16a leaves projection 54. The transistor 84 is biased off by the charge accumulated in condenser 100 when the condenser is charged by base current from transistor 84. When the condenser 100 dischargers through than required to hold transistor 84 turned off, the transistors 84 and 86 will turn back on. The transistors 62 and 82 will not turn olt' until the cam 16 rotates to a position where the projection 54 is approximately one-half the distance between cam lobes.

While the embodiments of the present invention as herein disclosed constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An ignition control circuit for controlling the application of power to an ignition system of an internal combustion engine comprising, a source of direct current, first and second conductors connected withopposite sides of said source of direct current, a voltage generating dedevice including a rotatable element driven by said engine connected in a magnetic circuit with said coil winding whereby pulses of voltage are induced in said coil winding in synchronismwith rotation-of said rotatable element, a transistor having an emitter, collector and base, an output circuit connected across said first and second conductors including the emitter-collector circuit of said transistor, said output circuit having an output terminal the voltage of which varies to control the application of power to said'ignition system, network connected across said first and second conductors including a resistor and a diode having a common junction, and means connecting said coil winding inseriesbetween said'junction of 'said voltage divider and the base of said. transistor, said diode connected in par.- allel with said coil winding and the emitter-base circuit'of said transistor, said resistor anddiode providing a potential at said junction which is just slightly less than the potential required to bias said transistor conductive between itsemitter and. collector when no voltage is induced in said coil winding, said coil winding generating an alternating voltage which durmgone-half cycle is added tothe bias. provided by said junction whereby the coil 56 to turn off the transistor 62 will occur when the projection 54 is at a the resistor 108 to a value lessa voltage dividerdur-..

cluding an element driven by said shaft and a coil supported by said base member, said coil having voltages induced therein in synchronism with rotation of said shaft and rotatable element, and an amplifier supported on said base member and mounted closely adjacent said coil, conductor means connecting said amplifier with opposite ends of said coil, said amplifier including first and second conductor means which are adapted to be connected across a source of direct current, a transistor having an emitter, collector and base, and a voltage divider comprised of a resistor and a diode; means connecting the collector and emitter of said transistor across said first and second conductors, said voltage divider connected in series across said first and second conductors and said resistor and diode having a common junction,

5 connected with said amplifier in cuit of said transistor which is means connectin junction and sai g said coil in series between said common d base of said transistor, said diode connected in parallel with said coil and the base-emitter circuit of said transistor, and at least one output conductor the emitter-collector ciradapted to control said ignition system for said engine.

References Cited UNITED STATES PATENTS MILTON O. HIRSHFIELD, Primary Examiner. I. D. MILLER, Assistant Examiner. 

1. AN IGNITION CONTROL CIRCUIT FOR CONTROLLING THE APPLICATION OF POWER TO AN IGNITION SYSTEM OF AN INTERNAL COMBUSTION ENGINE COMPRISING, A SOURCE OF DIRECT CURRENT, FIRST AND SECOND CONDUCTORS CONNECTED WITH OPPOSITE SIDES OF SAID SOURCE OF DIRECT CURRENT, A VOLTAGE GENERATING DEVICE INCLUDING A COIL WINDING, SAID VOLTAGE GENERATING DEVICE INCLUDING A ROTATABLE ELEMENT DRIVEN BY SAID ENGINE CONNECTED IN A MAGNETIC CIRCUIT WITH SAID COIL WINDING WHEREBY PULSES OF VOLTAGE ARE INDUCED IN SAID COIL WINDING IN SYNCHRONISM WITH ROTATION OF SAID ROTATABLE ELEMENT, A TRANSISTOR HAVING AN EMITTER, COLLECTOR AND BASE, AN OUTPUT CIRCUIT CONNECTED ACROSS SAID FIRST AND SECOND CONDUCTORS INCLUDING THE EMITTER-COLLECTOR CIRCUIT OF SAID TRANSISTOR, SAID OUTPUT CIRCUIT HAVING AN OUTPUT TERMINAL THE VOLTAGE OF WHICH VARIES TO CONTROL THE APPLICATION OF POWER TO SAID IGNITION SYSTEM, A VOLTAGE DIVIDER NETWORK CONNECTED ACROSS SAID FIRST AND SECOND CONDUCTORS INCLUDING A RESISTOR AND A DIODE HAVING A COMMON JUNCTION, AND MEANS CONNECTING SAID COIL WINDING 